Process for fractionating fast-pyrolysis oils, and products derived therefrom

ABSTRACT

A process is disclosed for fractionating lignocellulosic materials fast-prolysis oils to produce phenol-containing compositions suitable for the manufacture of phenol-formaldehyde resins. The process includes admixing the oils with an organic solvent having at least a moderate solubility parameter and good hydrogen 
     The United States Government has rights in this invention under Contract No. DE-AC02-83CH10093 between the United States Department of Energy and the Solar Energy Research Institute, a Division of the Midwest Research Institute.

The United States Government has rights in this invention under ContractNo. DE-AC02-83CH10093 between the United States Department of Energy andthe Solar Energy Research Institute, a Division of the Midwest ResearchInstitute.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the production of adhesiveresins from biomass materials and, more particularly, to the treatmentof fast-pyrolysis oils to make phenol-formaldehyde resins fromlignocellulosic materials. Specifically, the present invention relatesto a process for making phenol/neutral fractions suitable in theproduction of phenolformaldehyde resins from fast-pyrolysis oils derivedfrom lignocellulosic materials.

2. Description of the Prior Art

Adhesive resins are utilized in a wide variety of applications includingthe bonding of wood layers to manufacture plywood (resoles), theformation of molded pieces and articles (novolaks), and the like. Thereare certain disadvantages, however, to existing techniques for themanufacture of phenolic resins. Phenol has been traditionally derivedfrom petroleum-based products. Because the production of petroleum-basedphenol can be quite expensive, there have been efforts in recent yearsto at least partially substitute the phenol in such resins withinexpensive phenols derived from wood-based products or extracts. Morespecifically, phenols derived from bark, wood chips and the like hasbeen looked at as a potential substitute for petroleum-based phenol insuch resins.

The pyrolysis of biomass, and in particular lignocellulosic materials,is known to produce a complex mixture of phenolic compounds which arederived primarily from the lignin fraction of the biomass. In nature,lignin acts as an adhesive to bind the cellulose fibers together.Therefore, lignin and lignin-derived material from wood seem like anatural starting point for the development of biomass-based adhesiveresins. Sources for such phenolic materials include black liquor fromkraft pulping and other pulping processes, where the lignin is presentin a stream which is commonly burned to recover process heat andchemicals. Unfortunately, these lignins are generally not very reactiveafter recovery for a variety of reasons, such as high molecular weight,chemical modification during recovery due to condensation reactions andthe like, and lack of reproducibility of proprieties. Various types ofpyrolysis processes have also been utilized, frequently yielding similarkinds of results. Fast-pyrolysis, however, has proven to be an exceptionto this.

Fast-pyrolysis of biomass features the depolymerization of cellulosic,lignin, and hemicellulosic polymers which produces an oil having arelatively low molecular weight and which has considerable chemicalactivity under proper conditions. Crude pyrolysis oil apparentlyundergoes a limited amount of repolymerization upon physicalcondensation. However, the thermal stability of fast-pyrolysis oils atroom temperature is qualitatively quite good implying a good shelf lifefor the oils, although at 100° C. the crude oils solidify overnight.Solidified pyrolysis oils are characterized by their low strength andbrittleness. The potential of pyrolysis products for use in adhesiveresins is not a new concept, as indicated above, but the efficient andcost-effective reduction of this to practice has been an elusive goalover many years.

The general approach of producing phenols from biomass has previouslybeen to purify the phenolic fractions present in the pyrolysis oils bythe use of solvents to partition the constituents by differences insolubility and reactivity. Different variations of solvents, reagents,and sequence of extractions have been developed in the past, and thishas resulted in different partitioning coefficients for a couple ofhundreds of chemical compounds known to be in pyrolysis oils, andtherefore produced extracts having differing relative compositions.Another significant difference between various research effortspertaining to this area in the past has been the type of pyrolysis usedto produce the oils used as feed in the extraction process. Theseinclude updraft gasification, entrained fast-pyrolysis, and fluidizedbed fast-pyrolysis, all at atmospheric pressures, as well as slow, highpressure liquefaction processes. In addition, both hardwoods andsoftwoods have been used as feedstock in the past for the oil formingprocesses. These differences in extraction and pyrolysis processes,coupled with the differences in feedstock, yield different materials asproducts. Thus, as indicated below, the usefulness of a particularextract as an adhesive component is quite different, one from the other.

U.S. Pat. No. 4,209,647 and No. 4,223,465 disclose methods forrecovering phenolic fractions from oil obtained by pyrolysis oflignocellulosic materials and the subsequent use of that fraction inmaking of phenol-formaldehyde resins. However, these processes usepyrolysis oils which are usually formed at ill-defined temperatures andwhich have undergone phase separation cracking and some condensation,and suffer from very low yields.

A number of other patents including U.S. Pat. No. 2,172,415, No.2,203,217, No. 3,069,354, No. 3,309,356 and No. 4,508,886 as well asJapanese Patent No. 38-16895 all disclose a variety of processes forrecovering phenolic fractions from oils derived from biomass materialsand oil resources. These processes vary in the particular procedures andtechniques utilized to ultimately separate the phenolic fractions aswell as the procedures utilized to derive the oil from the biomass orother feed material. However, they all have a common thread linking themin that the ultimate end product is a phenolic fraction, which isdesired to be as pure as possible. This phenolic fraction is thenutilized to produce phenol-formaldehyde resins. The phenol substitutesusually were slower than phenol derived from petroleum-based products.The complex procedures disclosed in there references to producerelatively pure phenolic fractions are not particularly economical.Thus, there is still a need for a process designed to produce pyrolysisoils from lignocellulosic materials and then extract a phenoliccomposition from such oils which is capable of functioning asefficiently as petroleum-based phenols in the formation ofphenol-formaldehyde resins and which is less expensive to produce.

SUMMARY OF THE INVENTION

Accordingly, it is one object of the present invention to provide aprocess of producing a phenol-containing composition from biomassmaterial.

It is another object of the present invention to provide an improved andsimplified process of fractionating fast-pyrolysis oils derived fromlignocellulosic materials.

Another object of the present invention is to provide an inexpensivephenolic composition suitable for use in the production of adhesiveresins.

Yet another object of the present invention is to provide a process ofproducing a composition containing phenol and neutral fractions fromfast-pyrolysis oils.

To achieve the foregoing and other objects and in accordance with thepurpose of the present invention, as embodied and broadly describedherein, a process is disclosed for fractionating fast-pyrolysis oils toproduce phenol-containing compositions suitable for manufacturingphenol-formaldehyde resins. The process includes admixing the oils withan organic solvent having at least a moderate solubility parameter andgood hydrogen bonding capability, the solvent extracting the phenol andneutral fractions from the oils. The organic solvent-soluble fractioncontaining the phenol and neutral fractions is separated from themixture and admixed with water to extract water-soluble materialstherefrom. The organic solvent-soluble fraction is then separated fromthe water fraction and admixed with an aqueous alkali metals bicarbonatesolution to extract strong organic acids and highly polar compounds fromthe solvent fraction. Finally, the residual organic solvent-solublefraction is separated, and the organic solvent is removed therefrom toproduce phenol-containing compositions.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings which are incorporated in and form a part ofthe specification illustrate preferred embodiments of the presentinvention, and together with the description, serve to explain theprincipals of the invention. In the drawings:

FIG. 1 is a flow diagram illustrating the process of the presentinvention;

FIG. 2 is a graph illustrating sheer stress strength of resin adhesivesproduced from the end-products of the present invention compared to acommercial product; and

FIG. 3 is another graph illustrating wood failure test results of theadhesive resins produced from the end products of the process of thepresent invention compared to a commercial adhesive product.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

During the course of studying the problem of producing inexpensive buteffective phenolic compositions from biomass, it was discovered thatcertain polar organic solvents having at least a moderate solubilityparameter, moderate degree of polarity, and good hydrogen bondingcapabilities were capable of extracting both phenol and neutralfractions from fast-pyrolysis oils. Moreover, it was discovered thatthis extraction technique was equally effective for fast-pyrolysis oilsof differing starting materials. Thus, it was discovered that thepresent invention may be utilized with pyrolysis oils derived from pinesawdust, bark, grasses, softwoods as well as certain hardwoods with verylittle differences in the final results. Apparently, the fast-pyrolysisprocess preserves the delicate products in monomeric and oligomericstates. A key factor in the process of the present invention is that theoils derived from the lignocellulosic materials must be done soutilizing a fast-pyrolysis. Fast-pyrolysis is generally known in theart, and such a technique has been specifically disclosed in an articleentitled, "Production of Primary Pyrolysis Oils in a Vortex Reaction",American Chemical Society Division of Fuel Chemistry Preprints, Vol. 32,No. 2, pp. 21-28 (1987). Thus, details of such fast-pyrolysis techniquesneed not be specifically repeated and disclosed herein, and the contentsof this Article are therefore specifically incorporated herein byreference. Oils from other fast-pyrolysis concepts are also goodfeedstocks. Such concepts are referenced in "Fast-Pyrolysis ofPretreated Wood and Cellulose", Ibidem, pp. 29-35 (1987), "PreliminaryData for Scale up of a Biomass Vacuum Pyrolysis Reactor", Ibidem, pp.12-20 (1987); "The Role of Temperature in the Fast-Pyrolysis ofCellulose and Wood", Industrial Engineering Chemistry Research, Vol. 27,pp. 8-15 (1988), and "Oil From Biomass by Entrained Flow Pyrolysis",Biotechnology and Bioengineering Symposium, No. 14, pp. 15-20 (1984).

In general, the biomass solids in such fast-pyrolysis of biomass solidsentrain the feedstock particulates tangentially at high velocities intoa vortex reactor tube which has an internal surface design that guidesthe centrifuged solids into a tight helical pathway on the reactor wall.This results in a very high heat transfer to the wood or other feedstockparticles which allows mild cleavage of the polymeric components of thefeedstock. Consequently, high yields (greater than 55%) of dry woods andbark oils are generally obtained. If the feedstock is not fullypyrolyzed, the solids enter a recycle loop located at the end of thevortex reactor. After attrition to a powder, char particles elute withthe vapor stream and are isolated in a char cyclone. Alternative methodsto produce primary pyrolysis oils thought to be similar tofast-pyrolysis include fast-pyrolysis in fluidized beds and in entrainedflow reactors.

Utilizing the process of the present invention, the pyrolysis oils arefractionated in a unique way which produces a combined phenolics andneutral fraction of high phenolic hydroxyl and aldehyde content. Ingeneral, a polar organic solvent is added to the oils to separate thephenol and neutral fractions from said oils. The organic solvent-solublefraction is then admixed with water to extract water-soluble materials,and then further washed with an aqueous alkali metal bicarbonatesolution to extract strong organic acids and highly polar compounds. Theresidual organic solvent-soluble fraction containing the phenol andneutral fractions is then isolated, and the organic solvent is removed,preferably by evaporation, to produce a phenol-containing compositionhaving the phenol and neutral fractions of the original raw oils. Theyield of the phenolics and neutrals fraction in the extract is about 30%of the fast-pyrolysis oil derived from sawdust and about 50% of the oilderived from bark.

In prior art phenol-producing processes, the processes ended only afterthe phenolic-containing compositions were generally reduced to purifiedphenolics only, with the neutral fractions also be removed. By neutralfractions, it is meant those compounds which are not solubilized by astrong base such as sodium hydroxide, and have molecular weights ofapproximately 100-800. Such neutral fractions include carbonylcompounds, furfural-type compounds and the like. It was apparentlypreviously believed that such neutral fractions must also be extractedin order to provide a phenol composition which may be utilized as asubstitute for petroleum based phenols in the production ofphenol-formaldehyde adhesive resins. It has been discovered, however,that by utilizing the process of the present invention, the resultantcomposition containing both phenol and neutral fractions function justas well as and in some aspects better than relatively pure phenolcomposition in the production of phenol-formaldehyde resins becausesince the compositions have aldehyde groups, much less formaldehyde isneeded to make these formulations. Reduced formaldehyde levels lead tominimization of potential environmental problems. In addition, theeconomics are such that it is substantially less expensive tomanufacture the combined phenol and neutral fraction composition.Moreover, by utilizing the entire fraction which includes phenoliccompounds and neutral compounds as feedstocks for resins, we discoveredthat this prevented the pyrolysis-derived reactive phenolics fromundergoing air oxidation under alkaline conditions, which is whatprevails when one isolates and purifies the phenolics fraction alone.This latter air oxidation which can be a problem is a type of conditionthat prevails in many prior art techniques and is accomplished byextractions with aqueous sodium hydroxide solutions, and accompanied bythe formation of insoluble tars and reduced yields of phenolics.

Investigations of the fractionation scheme of the present invention asgenerally described above utilizing pine fast-pyrolysis oils werecarried out employing a number of different solvents to determine thepreferred and optimum solvents and the requirements thereof. In general,the whole oil was first dissolved in the organic solvent preferably inan oil:solvent ratio of 0.5:1 to 1:3 by weight. The oil was initiallyfiltered to separate char which is carried over from the pyrolysisreactor operations. Upon standing, the solvent/oil mixture thenseparates into two phases, the solvent-soluble phase and thesolvent-insoluble phase.

One requirement for the organic solvent is that the solvent and waterexhibit low mutual solubility. Preferably, acceptable solvents includethose with solubilities that are not more than about 10 grams of solventin 100 grams of water and about 3 grams of water in 100 grams ofsolvent, in terms of mutual solubility. Thus, this solvent requirementeliminates all low-molecular-weight alcohols (methanol, ethanol,propanol) that are infinitely soluble in water, methylethylketone, thecarboxylic acids (formic, acetic and propionic) which are infinitelysoluble in water, and methyl formate. The classes of solvents that wouldbe acceptable only from a pure mutual solubility point of view includehydrocarbons (aliphatic, aromatic), higher alcohols (greater than 6carbon atoms), higher ketones (greater than 5 carbon atoms), esters(greater than 2 carbon atoms), ethers, polychlorinated hydrocarbons, andhigher nitriles (greater than 4 carbon atoms).

Another requirement for the organic solvent which further limitspotential candidates is that the solvent have a low boiling point or alow-boiling point azeotrope. The preferred boiling point is around 100°C., although this is somewhat relative. Yet another requirement for theorganic solvent is that the solvent have some degree of polarity,preferably high polarity, as well as high hydrogen bonding capability inaddition to a moderate-to-good solubility parameter. The solubilityparameter is defined as a measure of all the intermolecular forcespresent in the solvent. The overall solubility parameter is composed ofcomponents due to dispersive forces, polar forces (caused by a highdipole moment in the molecule), and hydrogen bonding capability.Solubility parameters, measured in [cal/cm³ ]^(1/2), range from 5-7 forhydrocarbons and non-polar solvents, to 14.5 for methanol and 23.4 forwater-highly polar substances. Thus, low boiling point ethers, such asdiethyl ether, are excluded from being preferred solvents since theyhave a very low solubility parameters (7.4) and very low polarcomponents (1.4). Hydrocarbons are also excluded as preferred solventsbecause of their very low polar components and overall low solubilityparameters.

It has been found that the preferred group of solvents for use in thepresent invention include acetate and propionate esters, methyl alkylketones and ethyl alkyl ketones. More specific preferred organicsolvents are listed below in Table I, the most preferred being ethylacetate due to its availability, relatively low solubility in water, andhigh oil solubility. The most preferred range for solubility parametersincludes 8.4-9.1 with polar components in the 1.8-3.0 range and hydrogenbonding components in the 2-4.5 range. Additional acceptable solventsare the isomers of those listed in Table I. Mixtures of esters are alsoacceptable as are mixtures of the higher ketones. Ternary solventsystems also are possible, primarily mixtures of esters and highmolecular weight ethers such as diisopropylether to reduce the boilingpoint. However, the most preferred solvents for use with the presentinvention are ethyl acetate, as indicated above, as well as butylacetate and methylisobutylketone.

                                      TABLE I                                     __________________________________________________________________________                         Methyl       Ethyl                                                Acetate Esters                                                                            Ketones      Ketone                                        Property                                                                             Ethyl                                                                             Propyl                                                                            Butyl                                                                             i-Butyl                                                                           i-Amyl                                                                            i-Propyl                                                                           Ethyl                                       __________________________________________________________________________    Mol. wt  88.1                                                                              102.1                                                                             116.2                                                                             100.2                                                                             114.2                                                                             86.14                                                                              86.14                                       Boiling Point, °C.                                                              77.1                                                                              101.5                                                                             126.1                                                                             116.5                                                                             144 92   102.0                                       (at 70 mm Hg)                                                                 Density, 20° C.                                                                 0.90                                                                              0.89                                                                              0.88                                                                              0.80                                                                              0.88                                                                              0.81 0.81                                        Heat Vaporization,                                                            kcal/mole (20° C.)                                                              8.4 9.3 10.4                                                                              10.00                                                    kcal/mole (b.p.)                                                                       7.71                                                                              8.20                                                                              8.58                                                                              8.50    7.73 8.06                                        Solubility, wt %                                                                       8.08                                                                              2.3 0.43                                                                              1.7 ˜0                                                                          ˜2                                                                           2.4                                         in water                                                                      Water in 2.94                                                                              3.9 1.86                                                                              1.9 ˜0                                                                          ˜2                                                                           2.6                                         Azeotrope                                                                     Water wt %                                                                             9.47                                                                              14  28.7                                                                              24.3                                                                              44.0     24                                          boiling point, °C.                                                              70.38                                                                             82.2                                                                              90.2                                                                              87.9                                                                              94.7     82.9                                        Dielectric                                                                             6.02                                                                              6.00                                                                              5.01                                                                              13.11        17.0                                        Constant                                                                      Solubility param.                                                                      9.1 8.4 8.46                                                                              8.57                                                                              8.55                                                                              8.5  8.8                                         Total                                                                         Dispersive comp.                                                                       7.44                                                                              6.6 7.67                                                                              7.49                                                                              7.80     ˜7.8                                  Polar comp.                                                                            2.6 2.0 1.8 3.0 2.8      ˜3.4                                  H-Bonding comp.                                                                        4.5 4.8 3.1 2.0 2.0      2.0                                         __________________________________________________________________________

As indicated above, the preferred solvent is ethyl acetate, and theprocess of the present invention will hereinafter be described in termsof utilizing ethyl acetate as the solvent. However, it should beunderstood that any of the identified solvents may be utilized in thefollowing described process. As previously indicated the whole oil isdissolved in the ethyl acetate at a preferred pH of about 2-4 and thenfiltered. Upon standing, the ethyl acetate/pyrolysis oils mixtureseparates into two phases. Chemical spectroscopic analysis revealed thatthe ethyl acetate-insoluble fraction contains carbohydrate andcarbohydrate-derived products. The ethyl acetate-soluble fraction,containing the phenol/neutral fractions, is then separated and washedwith water to remove the remaining water-soluble carbohydrate andcarbohydrate-derived materials, preferably in a 1:6 to 1:1, water:oilweight ratio. The ethyl acetate-soluble fraction is then furtherextracted with an aqueous metal bicarbonate solution, preferably anaqueous sodium bicarbonate solution, 5% by weight. The pH of thebicarbonate extraction solution is preferably maintained atapproximately 8-9.5, and a 6:1 to 0.5:1 bicarbonate solution:oil weightratio is preferably utilized. The aqueous bicarbonate layer extracts thestrong organic acids and highly polar compounds, and the remaining ethylacetate-soluble layer contains the phenols and neutral fractions. Thisethyl acetate-soluble layer is then separated, and the ethyl acetatesolvent is evaporated using any known evaporation technique, includingvacuum evaporation techniques. The dried phenol/neutral fractiontypically contains 0.5-1% of water with traces of ethyl acetate. TableII illustrates typical yields for various pine sawdust fast-pyrolysisoils and fractions of oils obtained during different test runs as wellas for Douglas fir bark fast-pyrolysis oils.

                  TABLE II                                                        ______________________________________                                        Yields for Various Pyrolysis Oils                                                      Wt % Yields of Pyrolysis Oils Based on Dry,                                   Char-Free Oil                                                                   EtOAc   Water  Organic                                             Pyrolysis Oil                                                                            Insol   Sol.   Acids  Phenol/Neut.                                 ______________________________________                                        Pine sawdust                                                                             42.8    24.7   5.7    21.3.sup.a                                   Pine sawdust                                                                             28.2    39.sup.c                                                                             6.1    26.7.sup.b                                   Combined pine                                                                            22.8    28.9   6.7    25                                           oil.sup.d                                                                     Pine sawdust                                                                             41.sup.e                                                                              27.2   6.3    26                                           Douglas fir bark                                                                          0      12.1   15     Phenols:                                                                             Neutrals:                                                       Solids:2.9                                                                           47.8   15.6                                  Douglas fir bark                                                                          0      ND*    19     Phenols:                                                                             Neutrals:                                                       Solids:4.8                                                                           50.8   17                                    ______________________________________                                         .sup.a Phenolics: 16.5; Neutrals: 9.5                                         .sup.b Phenolics: 16.5; Neutrals: 6.0                                         .sup.c Water solubles by difference                                           .sup.d From two condensers                                                    .sup.e EtOAc insolubles by difference                                         *Not Determined                                                          

As indicated in Table II, the aqueous alkali metal bicarbonate solutionutilized to extract strong organic acids and highly polar compoundsfurther purifies the phenol/neutral fractions. While any suitable alkalimetal bicarbonate solution may be utilized, the preferred solution isselected from sodium bicarbonate, potassium bicarbonate, lithiumbicarbonate and ammonium bicarbonate, with sodium bicarbonate being thepreferred and most optimal solution. From the aqueous bicarbonatesolution, it is possible to isolate a fraction rich in organic acids asa by-product. In this instance, the aqueous layer can be neutralized,for example with 50% by weight of phosphoric acid (although other acidscan be used) saturated with sodium chloride, and extracted with ethylacetate. It is possible to then evaporate the solvents and isolate theremaining fractions as well.

The phenols/neutrals fraction can be further fractionated into isolatedphenolics and neutrals if desired. This can be accomplished by utilizinga 5% by weight solution of sodium hydroxide in a volume ratio of 5:1 ofsolution:extract. The aqueous layer is then acidified to a pH of about 2utilizing a 50% solution of phosphoric acid (although other acids can beused). It is then saturated with sodium chloride and extracted withethyl acetate. Evaporation of the solvent leads to the isolation of thephenolics fraction; evaporation of the initial ethyl acetate solutionfreed from phenolics leads to the neutrals fraction. It should be noted,however, that the present invention does not require this separation ofthe phenol from the neutral fractions, and it is in fact this aspect ofthe present invention which makes the present process so economic. Inthe past, as previously indicated, the phenolics have always been thedesired end-product, and sodium hydroxide has typically been utilized insuch process treatment. This is unnecessary with the process of thepresent invention, for it has been discovered that the combined phenolicand neutral fraction composition is sufficiently pure to function byitself in the formation of adhesive resins.

The process of the present invention can be operated in both batch modeas well as in a continuous mode. In the batch mode embodiment, the wholeoils are extracted with ethyl acetate and then washed with water.Following the water wash, the composition is then washed with theaqueous sodium bicarbonate to eliminate the acidic components, whichcome from pyrolysis of the carbohydrate fraction and would bedeleterious to the resins. In a continuous operation, the pyrolysis oilis preferably extracted simultaneously with water and ethyl acetate, andthen the ethyl acetate's soluble fraction is extracted countercurrentlywith the aqueous bicarbonate solution. The whole ethyl acetate fraction,which includes both phenolic and neutrals compounds, is then utilized asa feedstock for resins after solvent evaporation.

EXAMPLE I

1.0 kg of fast-pyrolysis oil derived from pine sawdust was dissolvedinto 1 kg of ethyl acetate. After filtration of the solution, thissolution then separated into two easily identified and separated phases.The ethyl acetate-soluble phase was then isolated, and 0.8 kg of waterwas added to this phase. The resulting water-soluble fraction wasisolated and saved for further processing. 2 kg of 5% sodium bicarbonatesolution was then added to the ethyl acetate-soluble fraction, and theaqueous phase therefrom was saved for further processing. This aqueousphase was the acids-soluble fraction. The resulting washed ethylacetate-soluble solution, containing the phenol and neutral fractions,was then solvent evaporated to remove the ethyl acetate solvent. Theyield of phenol/neutral was 31% by weight based on the dry oil.

The remaining ethyl acetate-insoluble fraction was solvent evaporatedand yielded 23 weight percent of the starting dry oil. The aqueous washyield after solvent evaporation was 39 weight percent of the oil. Theaqueous bicarbonate solution was neutralized with a 50% phosphoric acidsolution, and after saturation with sodium chloride, the organic phasewas extracted into ethyl acetate. After solvent evaporation, the acidsfraction yield was approximately 7 weight percent. FIG. 1 illustratesthis mass balance of the various fractions resulting from this Example Iutilizing the process of the invention.

EXAMPLE II

9.5 kg of fast-pyrolysis oils derived from pine sawdust were dissolvedinto 10 kg of ethyl acetate. After filtration, this solution settledinto two easily identified and separated phases. 1.8 kg of water wasthen added to the ethyl acetate-soluble phase, and this solution wasthen separated into two easily identified and separated phases. Theresulting water-soluble fraction was saved for further processing, andthe other ethyl acetate-soluble fraction was then admixed with 8.9 kg ofa 5% sodium bicarbonate solution. The aqueous phase of this solution wasthen separated and saved for further processing, which was theacids-soluble fraction. The resulting washed ethyl acetate-solublesolution, containing the phenol/neutral fraction, was separated, and thesolvent was then evaporated. The yield of the phenol/neutral fractionwas 30% by weight based on dry oil.

Using a procedure similar to that described above in Example I, the massbalance of the fractionation was determined as follows: the ethylacetate insoluble fraction comprise 21 weigjht percent, thewater-soluble fraction comprise 31 weight percent, and the organic acidscomprise 7.2 weight percent.

EXAMPLE III

The fractionation of Douglas fir pyrolysis products which are solids atroom temperature, was similar to that described for pine. 4.6 kg ofDouglas fir fast-pyrolysis product were dissolved into 9.8 kg of ethylacetate solution. No ethyl acetate insoluble fraction was observed. Thewhole solution was then extracted with 12 kg of a 5 weight percentaqueous sodium bicarbonate solution. The ethyl acetate-soluble solutioncontained 68 weight percent of phenolics and neutrals. The phenols andneutrals were then separated by extraction with 11 kg of a 5 weightpercent aqueous solution of sodium hydroxide. From the ethyl acetatesolution, 17 weight percent of neutrals were obtained. The alkalineaqueous solution, containing the phenolics, was acidified with 50%phosphoric acid, although other acids could have been used. Thissolution was then saturated with sodium chloride and extracted withethyl acetate to yield 50.8 weight percent for the phenolics fractionupon solvent evaporation. In the extraction with aqueous bicarbonatesolution, a precipitate was formed (5 weight percent) along with thesoluble acids fraction of 19 weight percent. The data for thefractionated materials are provided in Table II above.

EXAMPLE IV

Fast-pyrolysis oil derived from pine sawdust was also fractionated on acontinuous basis. The continuous process utilized, but is not limitedto, a 6-stage system of mixer tanks and settling tanks. The oil, ethylacetate, and water were mixed and allowed to settle with the organicphase being sent on to multi-stage extraction with 5 weight percentaqueous sodium bicarbonate solution with each extraction stage having aseparate settler tank. The bicarbonate extraction was run countercurrentto the flow of the organic phase. The aqueous fractions, that is thecombined ethyl acetate insoluble and water-soluble fractions, theaqueous bicarbonate solution, and the organic phase were all collectedand processed as described above. Conditions of the extraction includedthe following: oil flow, water flow, ethyl acetate flow, and aqueousbicarbonate flow rates were 10, 6, 34, and 35 mL/min, respectively. Itshould be noted, however, that the countercurrent continuous extractionprocess is not limited to these flow rates. The yield of phenol/neutralfraction composition was about 20% based on the oil flow rate andphenol/neutral isolated fractions. A total of 20 kg of oil wasfractionated in this way. Variations in flow rates and number of settlerand mixer tanks, however, can yield different proportions of materials.Phase separation was readily accomplished within the settlers.

Analysis of the products from intermediate stages of extraction revealedthat 1-3 stages of bicarbonate extraction may be used. Turning from theExamples given above, the fractionation scheme described above allowedthe isolation of 21% to 31% of the starting pine oils as aphenol/neutral fraction, or overall yields of 12-21% based on startingdry wood. This fraction consisted of approximately 73% phenolics,extractable from sodium hydroxide solution from an ethyl acetatesolution, and 27% neutrals. The total yield of phenol/neutral fractionisolation is reproducible as shown by the runs in Table II above.

The typical oil contained 6.2% phenolic hydroxyl and 0.4% carboxylicacid contents by weight ranges. Ranges of 5.5-6.5% phenolic hydroxyl and0.1-0.6% carboxylic acid contents are expected for the differentstarting feedstocks. The phenol/neutral fraction included about 6.6%phenolic hydroxyl content and no carboxylic acid content. Expectedranges for phenols/neutrals are 6.0-12% depending on the feed. The acidsfraction included about 9.2% phenolics and 0.9% carboxylic acidcontents. Ranges for various feedstocks are 5-10% for phenolics and0.5-3% carboxylic acid contents.

In characterizing the resultant phenol compositions, the apparentmolecular weight distributions obtained from gel permeationchromatography on polystyrene-divinylbenzene copolymer gels (50Angstrom) with tetrahydrofuran as solvent, indicated that the phenolicsfraction had components ranging from the monomeric substituted phenols(around 150) to oligomers (up to several thousand in molecular weight).The acids and neutrals had the lowest molecular weight components. Frommolecular beam mass spectra of the phenol/neutral fractions, a number ofphenolic compounds were detected: guaiacol (2-methoxyphenol) m/z 124;catechols m/z 110; isomers of substituted 2-methoxyphenols with alkylgroups such as methyl (m/z 138), vinyl (m/z 150), 3-hydroxy-propen(1)-yl(m/z 180), allyl (m/z 164), hydroxyethyl (m/z 168), and ethyl (m/z 152),most likely in the p-position. In addition, carbohydrate-derivedcompounds were present such as furfural alcohol and a number of otherfurfural derivatives.

From proton nuclear magnetic resonance spectrum of the phenol/neutralfraction, of the total intensity, the aromatic protons (6.5-10 ppm)constituted 52%, the aliphatic (1.5-3.5 ppm) about 20%, and the methoxyregion and oxygenated and side-chain region (3.0-4.2 ppm) constituted30%. This was in agreement with the description from the molecular beammass spectra of mixtures of phenolics with substituted groups. Thecarbon-13 nuclear magnetic resonance spectra confirmed this data.

Bark derived phenols have a very high phenolic hydroxy content(7.4-11.5%) depending on pyrolysis conditions (steam to nitrogen carriergas) and therefore are very suitable for adhesive formulation replacingphenol at greater than a 50% level.

As previously indicated, a principal purpose of producing thephenol/neutral fraction is to provide a substitute for pure phenol inthe production of resins and the like. Specifically, novolaks, which arephenol-formaldehyde resins made under acidic conditions, and resoles,which are phenol-formaldehyde resins formed under alkaline conditionsfor gluing to plywood, were produced and compared to novolaks andresoles utilizing standard formulations of commercially availablephenol. Specifically, phenol at a pH of 11 with twice the molar amountof formaldehyde was compared with Cascophen 313, a commercial softwoodplywood resin by Borden Chemicals. At 124° C., Cascophen 313 took 12.2min to gel, whereas the phenol with added paraformaldehyde did not geleven after 30 min.

Of the various fractions of pyrolysis oil, only the phenol/neutralfraction gave a positive gel test under the above conditions. Inpreliminary gel testing of the phenol/neutral extract, one gram ofparaformaldehyde was arbitrarily added to 4 grams of the extract. The pHof the extract was adjusted by adding 0.2-0.1 mL of 50% by weight sodiumhydroxide. There appeared to be a strong buffering of the pH by theextract at a pH 9.5. Cascophen 313 was used for comparison. At 0.5 mL ofadded sodium hydroxide, the gel time of the phenol/neutral fraction wasmuch shorter than that of the Cascophen, with a gel time of only 29%that of Cascophen at 124° C. At 112° C., it was 34%, while at 101° C. itwas 46% of Cascophen. At the original pH of 3 of the phenol/neutralfraction, there was no gelling of the mixture even at 132° C. with thesame amount of added paraformaldehyde.

Test novolak samples were then prepared and were characterized bysolid-state carbon-13 cross polarization/magie angle spinning nuclearmagnetic resonance (CP/MAS NMR) spectra as well as solution NMR. Thespectra of a phenol-formaldehyde novolak were compared with thereof asimilar novolak in which 50% by volume of the phenol was replaced withthe phenol/neutral fraction from fast-pyrolysis of pine sawdust inaccordance with the present invention. The authentic novolak producedmain peaks (from deconvolution) at 150, 130 and 120 ppm corresponding tohydroxysubstituted aromatic carbons, unsubstituted meta-aromaticcarbons, and unsubstituted para-aromatic carbons, respectively. In thealiphatic region, the main peaks were at 35 and 40 ppm, assigned toortho-para methylene bridges and para-para methylene bridges,respectively. The presence and intensity of such peaks corresponded tothe formation of random novolaks. On substitution of phenol with thephenol/neutral fraction produced in accordance with the presentinvention, the key peaks of the random novolak remained, but peakscharacteristic of the types of phenolic compounds present also appearedsuch as at 150 ppm (meta-aromatic carbons attached to methoxy groups),55 ppm (methoxy groups), and 20 ppm aliphatic groups.

Key differences between the authentic novolak and thephenol/neutral-substituted novolak produced from the process of thepresent invention were in relative peak intensities. While the ratio ofunsubstituted meta-aromatic carbons to ortho-para methylene bridges (130to 35 ppm) in the authentic sample was roughly 7:1, the ratio in thephenol/neutral novolak was approximately 4:1 (60% of the originalvalue). Such a difference was anticipated, since the phenol/neutralnovolak of the present invention contained a number of meta-substitutedmethoxy compounds. The phenolformaldehyde novolak had a high ratio ofhydroxy-substituted aromatic carbons (150 ppm) to unsubstitutedmeta-aromatic carbons (130 ppm) than the phenol/novolak of the presentinvention (40% vs 30%). Molding compounds have been made with thenovolaks developed with 50% replacement of phenol with phenols/neutralsthat had identical tensile and flexural strength and just slightly lowerIzod impact resistance. This latter parameter is controlled by the typefiller used and can be improved.

A few preliminary resoles have also been made utilizing a 50%replacement of phenol with the phenol/neutral fraction produced by theprocess of the present invention. FIG. 2 discloses a comparison ofstress shear strength between Cascophen and resoles produced withphenol/neutral fractions of the present invention. Specimens were testedafter a cold water soak (rightmost bar) and met test requirements. Ascan be seen from FIG. 2, the Cascophen showed a shear stress strength inpsi of approximately 700, while the resole with the phenol/neutralfraction produced from the present invention showed a strength ofapproximately 800 psi, significantly higher than Cascophen. Moreover,the resole produced from the phenol/neutral fraction of the presentinvention illustrated a cold soak strength of approximately 600, whichis considerably higher than the standard of 500 which has generally beenset for existing products such as the Cascophen. The tests performedused the British standard 1204; Part 1: 1964, and the testing of 10specimens per evaluation. Thus, FIG. 2 illustrates the fact that theshear strength of resins produced by substituting 50% of the phenolstherein with the phenol/neutral fraction produced with present inventionare in fact stronger than phenolformaldehyde resins utilizing purephenol.

Referring to FIG. 3, wood failure tests are compared between theCascophen and resoles having the phenol/neutral fraction produced fromthe present invention. To interpret FIG. 3, it should be understood thatit is preferred to have a wood failure, not a resin failure. Thus, ifthe wood fails, the resin is deemed to be good, and if the resin fails,it is deemed not to be good since the resin has actually separated.Thus, it is desirable to have a higher wood failure percent in order toshow resin strength. Referring to FIG. 3, it should be clear that theCascophen samples had a wood failure of approximately 38%, while theresin produced by substituting 50% of the phenolic portion with thephenol/neutral fraction from pyrolysis oils was well over 50%,illustrating a significant difference in resin strength capability.Moreover, the cold soak test results illustrated that the resole havingthe phenol/neutral fraction produced from the present invention had acold soak rating the same as a non-cold soak rating of the Cascophen.Thus, these tests further indicated that resole resins produced bysubstituting 50% of the phenol with the phenol/neutral fraction producedfrom the present invention are considerably better in function andstrength than standard commercially available products. The testsperformed used the British standard 1204: Part 1: 1964, and testing of10 specimens per evaluation.

With respect to the economic benefits of the present invention,petroleum derived phenol costs about $0.34 (spot price) and $0.40 (listprice) per pound. Prior to the present invention, the main competitionhas been the lignin-derived substitutes from commercial pulpingprocesses. Kraft lignins have to made chemically more reactive toreplace phenol in phenol-formaldehyde resins with similar performance.These commercial products are sold as resin co-reactants, and theirprice ranges from $0.33-$0.85 per pound depending on the reactivityneeded (based on kraft lignins). Less expensive products are availableas fillers in the $0.19 per pound range. The materials derived from theprocess of the present invention are co-reactants with the ability toreplace about 50% of the phenol in phenol-formaldehyde resins asdescribed above. Indications are that for molding compounds and forplywood adhesive resins, 50% phenol replacement would provide a verysimilar performance to the commercial phenolic adhesives, and in factwould give a better performance as illustrated and described above inFIGS. 2 and 3. However, there is a significant cost reduction factor inthat the phenol-formaldehyde fractions produced from the phenol/neutralcomposition of the present invention have an amortized cost projected atapproximately $0.16 per pound compared to $0.34-$0.40 per pound forcommercial phenol. If the lignocellulosic starting material is bark,this cost is even less because the yield of phenolics from the bark ishigher than that of sawdust or pine. Plant sizes were 250 to 1000 tonsof feedstock per day, 15% return on capital, plant life of 20 years, andwaste sawdust at $10.00 per dry ton.

As described above, the most developed application for the end-productsof the present invention is the replacement of 50% and potentially moreof phenol in phenol-formaldehyde resins for use as molding compounds,foundry, and shell moldings. Other potential applications for theresulting product of the process of the present invention include thereplacement of phenol in softwood and hardwood plywood resins, theinsulation market, composite board adhesives, laminated beams, flooringand decking, industrial particle board, wet-formed hard boards,wet-formed insulation boards, structural panel board, and paperoverlays. Alternative adhesive systems from the carbohydrate-richfractions of the present invention could also be made.

In addition, another product that can be derived from the otherfractions of the pyrolysis oils is an aromatic gasoline. Passage ofvapors of these compounds over zeolite catalysts produces high octanegasoline, as more clearly discussed in "Low-pressure upgrading ofPrimary Pyrolysis Oils form Biomass and Organic Waste", in Energy fromBiomass and Wastes, Elsevier Applied Science Publishers, London, pp.801-830 (1986).

A final advantage to the present invention is that about one-third ofthe usual amount of formaldehyde employed in conventional phenolicadhesives is necessary in producing adhesives wherein 50% of the phenolis substituted with phenol/neutral fractions provided by the presentinvention. Since there is significant environmental concern overformaldehyde emissions from resins, the products resulting from theprocess of the present invention therefore become very important fromthis context.

As can be seen from the above, a novel process for fractionatingfast-pyrolysis oils to produce phenol-containing compositions havingphenol/neutral fractions contained therein suitable for manufacturingphenol-formaldehyde resins are disclosed. The process is simple andeconomic, and can be used in either batch or continuous mode operations.The resulting phenol-neutral composition can be subsequently utilized toproduce novolaks and resole resins of comparable or superior performancecharacteristics relative to standard phenol-formaldehyde resins yet thepyrolysis-derived phenolic feedstocks are projected to cost less thanhalf of the cost of petroleum-derived phenol. Moreover, these resultingresins have numerous different types of applications, and the costbenefits alone are significant.

While the foregoing description and illustration of the presentinvention has been particularly shown in detail with reference topreferred embodiments and modifications thereof, it should be understoodby those skilled in the art that the foregoing and other modificationsare exemplary only, and that equivalent changes in composition anddetail may be employed therein without departing from the spirit andscope of the invention as claimed except as precluded by the prior art.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A process forfractionating fast-pyrolysis oils from biomass materials to producephenolic compounds/neutral fractions extract, wherein the neutralfractions have molecular weights of 100 to 800; said extract beingsubstitutable for a part of the phenol in phenol-formaldehyde resins,said process comprising:admixing said oils with an organic solventhaving a solubility parameter of approximately 8.4-9.1 polar componentsin the 1.8-3.0 range and hydrogen bonding components in the 2-4.8 range;separating the organic solvent-soluble fraction containing the phenoliccompounds/neutral fractions from said mixture and admixing it with waterto extract water-soluble materials therefrom; separating the organicsolvent-soluble fraction from said water fraction and admixing saidsolvent fraction with an aqueous alkali metal bicarbonate solution toextract strong organic acids and highly polar compounds from saidsolvent fractions; and separating the residual organic solvent-solublefraction and removing the organic solvent therefrom to produce saidphenolic compounds/neutral fractions extract.
 2. The process of claim 1,wherein said organic solvent also exhibits low mutual solubility withwater.
 3. The process as claimed in claim 1, wherein said organicsolvent is selected from the group consisting of acetate and propionateesters, methyl alkyl ketones and ethyl alkyl ketones.
 4. The process asclaimed in claim 3, wherein said organic solvent is selected from thegroup consisting of ethyl acetate, butyl acetate andmethylisobutylketone.
 5. The process as claimed in claim 4, wherein saidorganic solvent comprises ethyl acetate.
 6. The process as claimed inclaim 5, wherein the extraction utilizing ethyl acetate solvent isperformed at a pH of approximately 2-4.
 7. The process as claimed inclaim 1, wherein said aqueous alkali metal bicarbonate solution isselected from the group consisting of sodium bicarbonate, potassiumbicarbonate, ammonium bicarbonate and lithium bicarbonate.
 8. Theprocess as claimed in claim 7, wherein said bicarbonate solutioncomprises sodium bicarbonate.
 9. The process as claimed in claim 8,wherein the extraction utilizing said sodium bicarbonate solution iscarried out at pH of about 8.0-9.5.
 10. The process as claimed in claim1, wherein said oils are admixed with said organic solvent in anoil:solvent ratio of about 0.5:1 to 1:3 by weight.
 11. The process asclaimed in claim 1, wherein the organic solvent fraction is admixed withwater at a water:solvent ratio of approximately 1:6 to 1:1 by weight.12. The process as claimed in claim 1, wherein said organic solventfraction is admixed with said carbonate solution at a bicarbonatesolution:solvent ratio of about 6:1 to 0.5:1 by weight.
 13. The processas claimed in claim 1, wherein said organic solvent is removed from theresidual organic solvent fraction by evaporation to provide a dryphenol-containing composition.
 14. The process as claimed in claim 1,wherein said fast-pyrolysis oils are produced from lignocellulosicmaterials.
 15. The process as claimed in claim 14, wherein saidlignocellulosic materials are selected from the group consisting ofsoftwoods, hardwoods, pine sawdust, bark, grasses and agriculturalresidues.
 16. The process as claimed in claim 1, wherein said phenoliccompounds/neutrals fraction extract is capable of substituting for atleast approximately up to 50% of the phenol in phenol-formaldehyderesins.
 17. The process as claimed in claim 1, wherein said phenoliccompounds/neutrals fraction extract include a high phenolic hydroxyl andaldehyde content.
 18. The process as claimed in claim 1, wherein saidorganic solvent is evaporated from the residual organic solventfraction, and said phenolic compounds/neutrals fraction extract is driedto form the basis for resins for molding compounds, plywood, andparticle board.
 19. The process as claimed in claim 1, wherein theportion of said organic solvent/oil mixture not extracted into theorganic solvent-soluble fraction is further processed utilizing zeolitecatalysts to form gasoline.
 20. The process as claimed in claim 1,wherein said process is a batch process.
 21. The process as claimed inclaim 1, wherein said process is carried out on a continuous basis byperforming said organic solvent and water extractions simultaneouslywhile performing said alkali metal bicarbonate extraction in acountercurrent mode.
 22. A process for producing a combined phenoliccompounds/neutrals fraction extract fromfast-pyrolysis oflignocellulosic materials comprising: separating raw fast-pyrolysis oilsinto a carbohydrate-derived aqueous fraction and a phenolic-rich ethylacetate soluble fraction by admixing an ethyl acetate solvent with saidoils to extract the ethyl acetate-insoluble fraction; separating theethyl acetate-soluble fraction and washing it with water to furtherextract-soluble carbohydrates and derived polar compounds; separatingthe ethyl acetate-soluble fraction and washing it with an alkali metalbicarbonate solution to extract the ethyl acetate-soluble strong organicacids and highly polar compounds from said ethyl acetate fraction; andseparating said ethyl acetate fraction containing phenoliccompounds/neutrals fraction, and evaporating the ethyl acetate solventto produce a combined phenolic compounds/neutrals extract.
 23. Theprocess as claimed in claim 22, wherein said phenolic and neutralfraction composition is suitable for use as a phenol substitute for upto at least approximately 50% of the phenol composition ofphenolformaldehyde resins.
 24. The process as claimed in claim 22,wherein said alkali metal bicarbonate solution is selected from thegroup consisting of sodium bicarbonate, potassium bicarbonate, ammoniumbicarbonate and lithium bicarbonate.
 25. The process as claimed in claim24, wherein said aqueous metal bicarbonate solution comprises a sodiumbicarbonate solution at a pH of about 8-9.5.
 26. The process as claimedin claim 22, wherein said lignocellulosic materials are selected fromthe group consisting of softwoods, hardwoods, pine sawdust, bark,grasses and agricultural residues.
 27. The process as claimed in claim22, wherein said ethyl acetate solvent and said water are admixed withsaid oil simultaneously, and said alkali metal bicarbonate solution issubsequently flowed countercurrent to the ethyl acetate-soluble fractionto extract the soluble strong organic acids therefrom.
 28. The processas claimed in claim 22, wherein said ethyl acetate/oils solution has apH of about 2-4.
 29. A process for fractionation of components offast-pyrolysis oils comprising adding an ethyl acetate solvent to theoils to extract phenolic compounds/neutrals fraction into an ethylacetate-soluble fraction, washing the ethyl acetate-soluble fractionfirst with water to extract water-soluble carbohydrates and polarcompounds therefrom, extracting the ethyl acetate-soluble strong organicacids and highly polar compounds with a sodium bicarbonate solution,separating the ethyl acetate-soluble fraction containing a phenoliccompounds/aromatic neutrals fraction, and evaporating the ethyl acetatesolvent to produce a combined phenolic compounds/neutrals fractioncomposition.
 30. The improvement of claim 29, wherein said combinedphenolic compounds/neutrals composition is further treated with a sodiumhydroxide solution to extract the phenolic compounds fraction from theneutrals fraction of said composition.
 31. The improvement of claim 29,wherein said ethyl acetate/oils solution is at a pH of about 2-4, andsaid sodium bicarbonate solution/ethyl acetate-soluble fraction is at apH of about 8-9.5.